Two-stage absorption machine with first stage generator outside the main shell

ABSTRACT

The structural relationship of the two-stage generator absorption refrigeration machine having two shells is disclosed. A primary shell contains a low pressure generator, a condenser, an evaporator, and an absorber. A separate shell contains the high pressure generator.

United States Patent [56] References Cited UNlTED STATES PATENTS 6/1964Kaufmanet [72] Inventor John L. M. Holman Onalaska, W's. 802,706

3,398,548 8/1968 Cox et al....... 3,452,551 7/1969 Aronson........3,266,266 8/1966 Reid,Jr.

[21 Appl. No.

[22] Filed Dec. 20, 1968 [45] Patented June 8, 1971 [73] Assignee TheTrane Company La Crosse, Wis.

FOREIGN PATENTS 12/1965 Canada..........

Primary Examiner-William E. Wayner Attorneys-Arthur 0. Anderson, Lee E.Johnson and Carl M.

parate Lewis ABSTRACT: The structural relationship of the two-stage62/487 generator absorption refrigeration machine having two shells isdisclosed. A primary shell contains a low pressure genera- 62/489, tor,a condenser, an evaporator, and an absorber. A se 479, 497 shellcontains the high pressure generator.

2 0 l 5 3 b 5 2 F [54] TWO-STAGE ABSORPTION MACHINE WITH FIRST STAGEGENERATOR OUTSIDE THE MAIN SHELL 1 Claim, 4 Drawing Figs.

[51] Int.

[50] Field of PATENTEUJUH 812m 3.583177 sum 1 BF 2 INVENTOR.

JOHN L M. HOLMAN 82 73 74 ATTORNEY PATENTED JUN 8 I971 SHEET 2 OF 2TORNEY TWO-STAGE ABSORPTION MACHINE WITH FIRST STAGE GENERATOR OUTSIDETHE MAIN SHELL BACKGROUND OF THE INVENTION 1. Field of the InventionThis invention relates to a refrigeration machine, and more particularlyto a two shell, two stage generator, absorption refrigeration machine.

2. Description of the Prior Art Prior absorption refrigeration machineshave usually employed only a single stage generator or concentrator. Asthe absorption refrigeration technology has advanced, it has beenrealized that more efficient use of the heat input to such arefrigeration machine can be made by incorporating an additionalgenerator. Two generators are staged to produce a multiple effectmachine. Heat from a source such as high pressure steam is supplied to afirst stage generator and is returned to the steam source. Refrigerantvapor liberated from boiling absorbent in the first stage is fed to aheat exchanger in the second stage generator. This vapor condenses in aheat exchanger causing partially concentrated absorbent solution in thesecond stage to boil, thus further concentrating that solution. Thecondensate and the vapor are both fed to a condenser section for coolingand condensing.

Since the first stage generator is operating at a much higher pressurethan the remainder of the absorption machine, it is desirable toseparate this portion of the cycle from the remainder of the machine. Inaddition, if all five sections of the absorption cycle were to be placedin a single shell, the final product would become much larger thanpresent single stage absorption refrigeration machines of comparablecapacity.

SUMMARY OF THE INVENTION This invention therefore provides an absorptionrefrigeration machine comprising: a first fluidtight shell enclosing anevaporator section which contains a chilled medium heat exchange means;the chilled medium heat exchange means adapted to be connected to anarea being cooled; an absorber section containing a first cooling mediumheat exchange means, the first cooling medium heat exchange meansadapted to be connected to a source of cooled fluid, the absorbersection in vapor communication with the evaporator section; a lowpressure generator section containing a refrigerant vapor heat exchangemeans, the refrigerant vapor heat exchange means containing a vapor trapmeans for only allowing passage of liquid refrigerant, the low pressuregenerator section separated from the evaporator and the absorbersections by a fluidtight wall; a condenser section containing a secondcooling medium heat exchange means, the second cooling medium heatexchange means adapted to be connected to a source of cooled fluid, thecondenser section in vapor communication with the low pressure generatorsection and in liquid communication with the evaporator section and influid communication with the vapor trap means; a second fluidtight shellenclosing a high pressure generator section containing a heated mediumexchange means, the heated medium heat exchange means adapted to beplaced in communication with a source of heat energy, the high pressuregenerator section in liquid communication with the absorber section andin vapor communication with the refrigerant vapor heat exchange means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front view of thetwo-shell absorption refrigeration machine of the present invention.

FIG. 2 is a rear view of the absorption refrigeration machine of FIG. 1.

FIG. 3 is a view of the absorption refrigeration machine of FIG. I inwhich the front tube sheets ofthe two shells and the external pipinghave been omitted.

FIG. 4 is a side view of the main shell taken along section 4-4 of FIG.3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring jointly to FIGS. 1,2, and 3, the absorption refrigeration machine comprises a firstfluidtight shell 10 which encloses a condenser section 12, an evaporator14, an absorber l6, and a second stage generator, low pressure 20. Asecond fluidtight shell 35 encloses the first stage, high pressuregenerator 18.

The absorber I6 has a heat exchanger, comprising longitudinallyextending tubes 22, which is supplied with cooling fluid from a sourcenot shown through header 24. Connection with the conduit from thecooling fluid source is made with flange 25. Header 24 supplies all oftubes 22. The cooling fluid, which can be water which is evaporativelycooled by air, is conducted from header 33 by conduit 26 from the rearof the heat exchange tubes 22 to a header 27 which supplies heatexchange tubes 28 in condenser 12. Connection of conduit 26 with headers33 and 27 is made by means of flanges 32 and 34, respectively. A wall 29substantially encloses the condenser section. The cooling fluid leavesthe condenser though header 30 and returns to the cooling fluid sourcevia a conduit (not shown) connected to flange 31. It is understood ofcourse, that any of a variety of connections may be made with the heatexchangers of this machine without departing from the inventive concept;for example, heat exchangers 22 and 28 can be independently connected toa source of cooling fluid and each can be altered to produce a two-passeffect.

High pressure steam, or other heating medium, flows from a source suchas a boiler (not shown) into header 51 by connection with flange 36. Thesteam flows from header 52 into heat exchange tubes 37 in high pressuregenerator 18. End plate 38 has a dual function; it serves not only asthe end plate which seals the ends of shell 35, but also is the tubesheet for heat exchange tubes 37. End plate 39 serves the same purposeat the opposite end of the generator 18 and additionally providesconnection with conduit 40. Heat exchange tubes 37 terminate within endplate 39 and in fluid communication with header 4]. A restrictor meansis normally attached to flange 42 to prevent escape of steam from theheat exchange tubes 37 until it has condensed, allowing substantiallyonly condensate to leave heat exchange tubes 37. This restrictor meanscan be any suitable steam flow restrictor such as an orifice or a floatvalve. Alternatively, the restrictor can be mounted within the generator18. Heat from condensing steam in the heat exchange tubes 37 causesdilute absorbent solution present in the first stage generator to boil.The steam condensate from the aforementioned restrictor means flows backto the steam generating source. It is to be understood, of course, thata combustible fluid, direct fired, heat exchange or other suitableenergy source can be substituted for the heat exchange tubes 37 withoutsubstantially modifying the principals of construction of thisinvention.

Various types of refrigerants and absorbents may be used in the presentmachine. A solution oflithium bromide absorbent in a refrigerant such aswater is satisfactory. The term concentrated solution as used hereinmeans a solution which is concentrated in an absorbent. A weak solution"is a solution dilute in absorbent. A solution having a concentrationbetween that of a concentrated solution and a weak solution is termed anintermediate strength solution.

The refrigerant vapor generated in the first stage generator 18 flowsthrough conduit 40 and into the second stage low pressure generator 20.Conduit 40 is connected to flanges 52 and 53, the latter of which allowsaccess to header 43. The refrigerant vapor flows from header 43 intoheat exchange tubes 44. The refrigerant vapor condenses and releasesheat to further concentrate intermediate strength solution present inthe second stage generator 20. A flow regulating device in the form ofan orifice or a trap 45 regulates the flow of refrigerant from the heatexchange tubes 44 into the condenser I2.

Trap 45 is connected with heat exchange tubes 44 via header 46 ontowhich it is attached at flange 47. Condensed refrigerant from heatexchanger tubes 44 enters the condenser at a connection 48 above header30. The difference in pressure between the condenser and heat exchangetubes 44 forces the condensed refrigerant from the tubes 44 into thecondenser 12. Trap 45 functions to prevent flow of any refrigerant vaporfrom heat exchange tubes 44 into the condenser 12. The vapor producedfrom the boiling intermediate strength solution in the second stagegenerator passes through eliminators 49 where it is condensed into aliquid in condenser 12. Eliminators 49 remove entrained liquid from thevapor. Liquid refrigerant flows from the condenser through opening ororifice 50 into evaporator 14.

The liquid refrigerant is evaporated in evaporator 14, thus removingheat from the fluid in heat exchange tubes 61. The refrigerant vaporproduced passes through eliminators 62 to remove entrained liquid andinto the absorber section 16. Unevaporated liquid refrigerant iscollected in pan 60, from which it enters conduit 63, and isrecirculated by pump means 64 through conduit 65 into spray header 66.From header 66 the liquid refrigerant is sprayed over heat exchangetubes 61 through spray nozzles 67. Fluid from a heat load is circulatedthrough heat exchange tubes 61 by connection with flanges 70 and 71 onheaders 69 and 68 respectively. The fluid circulated through heatexchange tubes 61 is cooled by the evaporating refrigerant. It isthereafter returned to the heat load.

Absorbent solution present in absorber 16 absorbs refrigerant vaporproduced in evaporator 14. The solution from the absorber 16 flowsthrough a conduit 72 in the bottom of the absorber section. Theabsorbent solution from conduit 72 is circulated by pump 73 throughconduit 74, a low temperature heat exchanger 75, a high temperature heatexchanger 76, and conduit 77 from which it enters high pressuregenerator l8.The absorbent solution flowing into generator 18 ispartially concentrated therein.

The partially concentrated solution from high pressure generator 18flows through conduit 78 to high temperature heat exchanger 76 in whichit gives up heat to weak solution flowing into conduit 77. It then flowsthrough conduit 79 into low pressure generator 20, in which it isfurther concentrated. The concentrated solution from the second stagegenerator 20 flows through conduit 80, through low temperature heatexchanger 75 into conduit 81 which is connected to the inlet of pump 82.Dilute solution flowing from absorber 16 through conduit 83 also entersthe inlet of pump 82 where it is mixed with the concentrated solutionflowing from conduit 81. The weak and concentrated solutions are mixedin pump 82 and are forced through conduit 84 to spray header 85, fromwhich it is distributed over heat exchange tubes 22 by spray nozzles 86.

It will be understood by one skilled in the absorption refrigeration artthat motive power is necessary to drive pumps 64, 73, and 82. Thepreferred power source is, of course, an electric motor. Each pump canbe driven by a separate motor, or a single motor can be employed todrive all pumps with a single shaft.

Referring now to FIGS. 3 and 4, the internal arrangement of thecomponents sections of the absorption machine will be further described.The numerals in FIG. 4 correspond to those utilized in the precedingfigures. High temperature generator 18 can have a length equal to thatof main shell 10. ln this embodiment generator shell 35 has an uppercircular section and a lower liquid tank section 91. Partiallyconcentrated absorbent solution is collected in tank 91 before it flowsinto conduit 78. Refrigerant vapor produced in high pressure generator18 flows through opening 54 into conduit 40. Intermediate strength flowsinto low temperature generator 20 through conduit 79. Concentratedsolution flows out of low temperature generator 20 through weir 92 intocompartment 93. From this compartment the concentrated absorbentsolution flows into conduit 80. Compartment 93 can extend the fulllength of the shell 10. More than one weir 92 can be employed, or theweir 92 can extend the full length of the shell 10. The liquideliminators 49 are a series of spaced parallel plates positioned asshown in FIG. 3 so that the leading edge of one plate overlaps thetrailing edge of a next adjacent plate. This construction provides atortuous path for refrigerant vapor entering the condenser whichfacilitates removal of entrained liquid refrigerant.

It will be noted that all of the heat exchange tubes are longitudinallyextending relative to the main shell 10 and genera tor shell 35. The endplates 94 and 95 attached at the end of shell 10 serve a dual function.They seal and form the end portions of the various compartments withinthe shell. Furthermore, teat exchange tubes extend through to theoutside of end plates 94 and 95. Thus the end plates form the tubesheets for all of the heat exchangers in primary shell 10. The headers24, 27, 30, 33, 43, 46, 68, and 69 are then mechanically attached tothese end plates for distributing the various fluids through the heatexchange tubes.

The absorber section 16 is in vapor communication with the evaporatorsection 14. Condenser 12 is in liquid communication with the evaporatorsection 14 through the orifice 50. The condenser 12 receives refrigerantliquid from heat exchange tubes 44 via connection 48 and is also invapor communication with the low pressure generator 20 through liquideliminators 49. The relative arrangement of the sections as shown in H6.3 are preferred, that is, the low pressure generator and condensersubstantially horizontally contiguous in the upper portion of the mainshell, the absorber in the lower portion of the main shell, and theevaporator above the absorber. The high pressure generator is located toprovide a liquid level therein above any liquid level existing in themain shell. However, other arrangements of the low pressure generator,the condenser, the evaporator, and the absorber within the main shell 10can be made without departing from the present invention. Of course, theshells 10 and 35 need not be of the cylindrical cross section as shown.They may be of any desired cross section; however, the cylindrical shapeis most desirable.

Of course, flow, pressure, safety, and miscellaneous control arenecessary for proper operation of the absorption refrigeration machinedisclosed above. For an example of an appropriate control mechanism forthe instant machine, refer to the copending application, Ser. No. 785,51I, filed Dec. 20, I968, incorporated herein by reference.

The utility and need for the absorption refrigeration machine of thisinvention are apparent from the foregoing description. Therefore, what Iclaim is:

1. An absorption refrigeration machine comprising first and secondfluidtight shells; said first shell including an evaporator sectioncontaining a chilled medium heat exchange means adapted to be connectedto an area to be cooled; an absorber section below said evaporatorsection and in vapor communication therewith, said absorber sectioncontaining a heat exchange means adapted to be connected to a source ofcooled fluid; a low pressure generator section containing a refrigerantvapor heat exchange means communicating with a vapor trap means forallowing passage of only liquid refrigerant therethrough, said lowpressure generator section separated from said evaporator section andsaid absorber sec tion by a fluidtight wall; and a condenser sectioncontaining a heat exchange means adapted to be connected to a source ofcooled fluid, said condenser section located above said evaporatorsection and said absorber section and in fluid communication with saidvapor trap means, in vapor communication with said low pressuregenerator section, and in liquid communication with said evaporatorsection; said second shell including a high pressure generator sectioncontaining a heat exchange means adapted to be connected to a source ofheat, said high pressure generator section being in vapor communicationwith said low pressure generator section and in liquid communicationwith said absorber section; said second shell being located sufficientlyabove said first shell to insure that the liquid level in said secondshell is above any liquid level in said first shell during operation ofsaid refrigeration machine.

1. An absorption refrigeration machine comprising first and secondfluidtight shells; said first shell including an evaporator sectioncontaining a chilled medium heat exchange means adapted to be connectedto an area to be cooled; an absorber section below said evaporatorsection and in vapor communication therewith, said absorber sectioncontaining a heaT exchange means adapted to be connected to a source ofcooled fluid; a low pressure generator section containing a refrigerantvapor heat exchange means communicating with a vapor trap means forallowing passage of only liquid refrigerant therethrough, said lowpressure generator section separated from said evaporator section andsaid absorber section by a fluidtight wall; and a condenser sectioncontaining a heat exchange means adapted to be connected to a source ofcooled fluid, said condenser section located above said evaporatorsection and said absorber section and in fluid communication with saidvapor trap means, in vapor communication with said low pressuregenerator section, and in liquid communication with said evaporatorsection; said second shell including a high pressure generator sectioncontaining a heat exchange means adapted to be connected to a source ofheat, said high pressure generator section being in vapor communicationwith said low pressure generator section and in liquid communicationwith said absorber section; said second shell being located sufficientlyabove said first shell to insure that the liquid level in said secondshell is above any liquid level in said first shell during operation ofsaid refrigeration machine.